package ca.utoronto.cms.cscc85.project4.teamrf;

import java.io.*;
import android.content.Context;
import android.database.SQLException;
import android.database.sqlite.*;

/**
 * This class sets up the database for us. So when ever we need a connection to hte database, we call the static
 * method opendatabase().
 *
 */
public class DBHandler extends SQLiteOpenHelper {		 
    // path to app's database in data folder
    private static String DB_PATH = "/data/data/ca.utoronto.cms.cscc85.project4.teamrf/databases/";
    private static String DB_NAME = "recipes";  //database name
    public SQLiteDatabase myDataBase; //database object
    private final Context myContext; 
 
    /**
     * Constructor
     * Takes and keeps a reference of the passed context in order to access to the application assets and resources.
     * @param context
     */
    public DBHandler(Context context) {
 
    	super(context, DB_NAME, null, 1);
        this.myContext = context;
    }	
 
    /**
     * Creates a empty database on the system and rewrites it with your own database.
     *
     * */
    public void createDataBase() throws IOException{ 
    	boolean dbExist = checkDataBase();
 
    	if(dbExist){
    		//do nothing - database already exist
    	}else{ 
    		//By calling this method and empty database will be created into the default system path
               //of your application so we are gonna be able to overwrite that database with our database.
        	this.getReadableDatabase();
 
        	try { 
    			copyDataBase(); 
    		} catch (IOException e) {
        		throw new Error("Error copying database"); 
        	}
    	}
 
    }
 
    /**
     * Check if the database already exist to avoid re-copying the file each time you open the application.
     * @return true if it exists, false if it doesn't
     */
    private boolean checkDataBase(){
 
    	SQLiteDatabase checkDB = null; 
    	try{
    		String myPath = DB_PATH + DB_NAME;
    		checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE); 
    	}catch(SQLiteException e){ 
    		//database does't exist yet. 
    	} 
    	if(checkDB != null){ 
    		checkDB.close(); 
    	} 
    	return checkDB != null ? true : false;
    }
 
    /**
     * Copies your database from your local assets-folder to the just created empty database in the
     * system folder, from where it can be accessed and handled.
     * */
    private void copyDataBase() throws IOException{
 
    	//Open your local db as the input stream
    	InputStream myInput = myContext.getAssets().open(DB_NAME);
 
    	// Path to the just created empty db
    	String outFileName = DB_PATH + DB_NAME;
 
    	//Open the empty db as the output stream
    	OutputStream myOutput = new FileOutputStream(outFileName);
 
    	//transfer bytes from the inputfile to the outputfile
    	byte[] buffer = new byte[1024];  
    	int length;   
    	while ((length = myInput.read(buffer))>0){   
    		myOutput.write(buffer, 0, length);   
    	}   
 
    	//Close the streams
    	myOutput.flush();
    	myOutput.close();
    	myInput.close();
 
    }
 /**
  * Open connection to the database for other applications to use.
  * @throws SQLException
  */
    public void openDataBase() throws SQLException { 
    	// open the database
        String myPath = DB_PATH + DB_NAME;
    	myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
    }
 
    @Override
    /**
     * Closes the database
     */
	public synchronized void close() {
    	// close the database
    	if(myDataBase != null)
    		myDataBase.close();
 
    	super.close();
 
	}
 
	@Override
	/**
	 * methods that must be override but not used
	 */
	public void onCreate(SQLiteDatabase db) {
 
	}
	
	@Override
	/**
	 * methods that must be override but not used
	 */
	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
 
	} 
}